The present invention relates to a method of controlling lineup of tools in numerical control machine tool such as machining center.
Hitherto, for effecting a predetermined machining in a machining center, it has been necessary to give to the machine an instruction concerning the tool to be used to accomplish a desired machining shape at the time machining was to be carried out. Therefore, it has been an ordinary measure for a programmer to work out the machining program to be executed by the machining center including the specific details of the kinds of tools to be used and the sequence of the use of these tools optimum for obtaining the final shape shown in drawings depicting the desired shape of the finished product. Such a detailed programming process, however, takes much labor and time and, in addition, requires a skilled programmer having abundant knowledge in the field concerned, in addition to the operator who actually manages the machine, in order to obtain satisfactory operation of the machine. This impractically restricts the widespread use of such machining centers.
Under this circumstance, an arrangement has been provided for facilitating the programming of a machining center. The machining is sorted according to the machining shape into three modes: namely, a point machining mode, line machining mode and a surface machining mode, each machining mode being further classified into a plurality of machining units and, as the operator inputs the machining shape shown in the drawings in terms of these machining units, the machining program is automatically formed in the machine and the machine executes the machining in accordance with the thus formed machining program, so that the necessity for the programming by a programmer is eliminated to obviate the above-described problem of the prior art. According to this method, the drill hole machining unit for example is composed of three machining elements: namely, a center drilling, drill boring and chamfering. The drill hole machining, therefore, is performed by using a spot drill, drill and a chamfering cutter in the mentioned order. In the case where a machining operation employs a number of such machining units which are executed sequentially in the appointed order, it is often experienced that the machining element to be performed by an identical tool is performed repeatedly in various portions of the series of machining, resulting inconveniently in an increased frequency of demounting and mounting of such tool on the machine spindle and, hence, in an unnecessarily long machining time for completing the machining.